Wireless communication technologies have seen tremendous growth in the last few years. This growth has been fueled in part by the freedom of movement offered by wireless technologies and the greatly improved quality of voice and data communications over the wireless medium. Improved quality of voice services along with the addition of data services have had and will continue to have a significant effect on the communicating public.
One type of service enjoying growth has been data service over portable communication devices, especially the delivery of high speed wireless data to mobile and fixed terminals. TIA/EIA/IS-856 “cdma 2000 High Rate Packet Data Air Interface Specification”, 1×EV-DO is an air interface optimized for the delivery of high-speed wireless data to mobile and fixed terminals.
Data transmission differs from voice transmission in several key aspects. Voice transmissions are characterized by low, fixed and constant delays. However, voice transmission is more sensitive to delay with long latencies above 100 msec being intolerable. Voice transmissions also tend to be more tolerant of bit errors and symmetric in the forward and reverse directions.
Data transmission is more tolerant of delays and delay variation than voice transmission. However, data transmission is less tolerant of bit errors and is asymmetric in the forward and reverse directions. In addition, data transmission is “bursty”, especially when data is downloaded to a user.
Typically, a user requests information, such as a web page download when using a data system, such as 1xEV-DO. The data is sent to the user in “bursts” containing packets of the desired data. Data is arranged in a sequence of packets for transmission. Correct reception of the packets is crucial for using and manipulating the requested data. To insure that the user receives the data correctly a series of acknowledgements is sent to the source of the transmissions. These acknowledgments indicate which packets have been received and correctly decoded by the user's unit. In general, an acknowledgement channel or ACK channel is used for these transmissions with packets being acknowledged three slots after receipt. If a packet is not received correctly, a retransmission request is made and the packet retransmitted. Delay in retransmission can result in resending of packets that have been correctly received. Retransmission of packets increases delay and can negatively affect the user experience. Therefore, there is a need for an efficient method for acknowledging packet transmissions in a communication system.